178 



LECTURES ON THE CENTRAL NERVOUS SYSTEM. 



Next, you will notice that the lateral horns are strongly 

 developed. The accessory nerve of Willis arises from cells 

 which here lie at their hase, hut which, at higher levels, are 

 situated at the lateral boundary of the anterior horns. The 

 root-fibres of this nerve, which are srivcn off continuously from 



O v 



the level of the sixth cervical nerve up to the commencement 

 of the ohlongata, do not pass straight out, as might be supposed, 



wg 



FIG. 107. 



Cross-section of medulla oblongata through the pyramidal decussation. Fpy, pyra- 

 midal column ; Cga, anterior horn ; Fa', remains of anterior column ; Ng, nucleus of the 

 funiculus gracilis ; g, substantia gelatinosa; XI, accessory nerve. (After Henle.) 



from the cut, but, on the contrary, extend upward toward the 

 brain and then bend outward at an angle (Darkschewitsch). 

 Only the horizontal limb of this angle is shown in the section 

 (106). Please notice, too, that in the space between the posterior 

 and anterior horns the gray matter extends out into the lateral 

 column in the form of a thick net-work of fasciculi. This net- 

 work is insinuated among the bundles of the lateral column, and 

 is called the processus reticularis. 



